Objective:

There are three primary objectives for this proposed project. A description
of each of the three objectives is followed by a brief description of the
approach. The first objective is to extend the mechanistic studies of
photoinhibition and UV inhibition of primary productivity initiated at the
University of California laboratory. The target sites for UVB regulation in
local waters will be identified. The primary focus will be on photoinhibition of
photosynthesis with the first test modeled on that of Kroon, using
Pulse-Amplitude-Modulation fluorimetry techniques. Following this, there will be
genetic analysis of DNA damage following procedures outlined by Jovine and
Prezelin.

The second objective is to assess the impact of fluctuating ozone levels (and
resulting UVB fluctuations) on primary productivity at temperate latitudes. To
accomplish this, a long term database of biweekly measurements of UV sensitivity
of regional phytoplankton communities to discern the seasonal variables in
sensitivity; discern the most sensitive phytoplankton groups; and create a
bio-optical database for natural communities to derive and test models.

The third objective is to develop biological weighing functions for temperate
latitude phytoplankton, and compare these studies with work in other aquatic
ecosystems in order to develop accurate bio-optical models for general use.
Combining spatial and temporal data for UVB dose rates with the appropriate
biological weighing functions for UV inhibition of temperate phytoplankton will
provide the necessary information required for models to predict the direction
and magnitude of UVB induced changes. These can then be compared with models
developed for other ecosystems.

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.